The wireless telecommunications industry has been experiencing a tremendous growth and an important transition period in the past few years and, as a result, is often characterized by fierce competition between wireless service providers. In an attempt to increase revenues and profits, it is generally important for the service providers to provide better services with lower costs.
A wireless telecommunication network consists of a wireless access network and a wireless core network. The wireless access network allows subscribers access to the network through its Radio Frequency (RF) equipment so that telecommunication services can be delivered to subscribers. Wireless core networks generally provide the network functionalities other than RF to subscribers, including mobility management, voice call management, packet session management, and transport for voice and data traffic.
FIG. 1 illustrates a GSM/GPRS network 100. Wireless networks of other technologies are similar to the one shown in FIG. 1. As shown in FIG. 1, different types of core network elements, such as BSCs 110, MSCs 112, GMSCs 114, SGSNs 116, and GGSNs 118, work together with RF equipment at Base Transceiver Stations (BTSs) 120 to provide telecommunication services to subscribers. In a typical wireless network, there are a number of BTSs with RF equipment for providing wireless network access to subscribers. A BTS provides RF coverage of a certain geographic area where subscribers' Mobile Stations (MSs) are able to place and receive telephone calls and packet data (e.g., emails).
When a subscriber places or receives a voice call in the coverage area of a BTS, the wireless network establishes a wireless connection between the subscriber's MS and the BTS. If the subscriber moves around, the subscriber may leave the coverage area of the BTS, and enter the coverage area of another BTS. In this case the wireless network performs a procedure called handover, where the first BTS hands over the subscriber's voice call to the second BTS. Due to the mobility of mobile subscribers, there are a number of handovers between adjacent BTSs, especially in those heavy mobility areas.
BTSs are controlled by a type of core network equipment, named Base Station Controller (BSC). BSCs provide mobility management functionality to the network. A BSC has a parent-to-child (one-to-multiple) relationship to the BTSs that it controls. BTSs controlled by a BSC form the serving area of the BSC. BSCs are connected to a type of core network equipment, called a Mobile Switching Center (MSC). MSCs provide voice call processing and switching functionality to subscribers. An MSC has a parent-to-child (one-to-multiple) relationship to the BSCs to which it is connected. The BSCs connected to an MSC form the serving area of the MSC.
BSCs are also connected to another type of core network equipment, called a Serving GPRS Support Node (SGSN). SGSNs process packet data traffic, and provide mobility management and packet data services to subscribers. An SGSN has a parent-to-child (one-to-multiple) relationship to the BSCs to which it is connected. The BSCs connected to an MSC form the serving area of the SGSN.
A Home Location Register (HLR) is a database storing subscriber profiles and locations in terms of MSC serving areas. A Gateway MSC (GMSC) provides gateway functionality between wireless networks and the wired network Public Switching Telephony Network (PSTN). A Gateway GSN (GGSN) provides gateway functionality between wireless networks and fixed data networks (e.g., the Internet). Network elements in a typical wireless network as illustrated in FIG. 1 are connected through different types of transport facilities, such as T1s, T3s, OC-3, OC-12, and OC-48.
A network configuration refers to a particular parent-to-child connectivity between different types of network equipment at different levels, such as BSC-to-BTS relationships, MSC-to-BSC relationships, SGSN-to-BSC relationships, and so forth. When those relationships are changed, it is considered that the network is evolved to a new network configuration.
As the number of subscribers grows, more network equipment needs to be deployed for accommodating the forecasted network traffic. In a GSM/GPRS network, for example, additional BTSs may be planned to be introduced, and the traffic on the existing BTSs may also grow. As a consequence, additional core network equipment, such as BSCs, MSCs, and SGSNs, needs to be deployed. The BTS-to-BSC, BSC-to-MSC, and BSC-to-SGSN parenting relationships need to be adjusted so that the capacity of the core network equipment is utilized to its maximum level and the network is maintained at a high performance level. Maximum network capacity with additional equipment is achieved by balancing the equipment load across the network through serving area adjustments. The serving areas of the BSCs, MSCs and SGSNs in the network are adjusted through network element re-homes, which are the re-assigning of those network nodes to different parenting equipment.
Preferred embodiments of the present invention provide methods and systems for minimizing the total cost of ownership for wireless core networks while maintaining high network performance. In other words, preferred embodiments of the invention minimize the total cost of deploying, operating and maintaining a wireless core network. These methods and systems generally model wireless core networks, analyze the total cost of maintaining the networks, and provide an optimal network configuration with lowest total cost of ownership while guaranteeing high network performance.
Preferred embodiments of the present invention provide a mathematical model for calculating the total cost of ownership of a wireless core network for a given time period. The model reflects the different types of cost for owning a wireless core network, including network equipment cost, customer acquisition and retention cost, facility leasing cost, and network engineering cost. The model also characterizes the total cost of ownership as the core network evolves over time to cope with subscriber growth and mobility pattern changes.
Preferred embodiments of the present invention provide methods and systems for minimizing the total cost of ownership for wireless core networks. A multi-level server area optimization algorithm is applied to different types of wireless core networks, such as GSM, GPRS, CDMA and UMTS, for determining optimal equipment serving areas which result in the lowest total cost of owning a core network at any given time. A recursive algorithm is defined to optimize sequencing of the network configuration that minimizes total cost over time across the network planning horizon.
It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other system or methods for carrying out the same purposes of preferred embodiments of the present invention. It should also be realized by those skilled in the art that such equivalent systems and methods do not depart from the spirit and scope of preferred embodiments of the invention as set forth in the appended claims.